Question 3
#Building with time independent objects
survTimeIndep <- Surv(burn1$T3, burn1$D3)
#Build a cox model with just treatment
burn.cox.indep.T <- coxph(survTimeIndep ~ Treatment, data = burn1)
summary(burn.cox.indep.T)
## Call:
## coxph(formula = survTimeIndep ~ Treatment, data = burn1)
##
## n= 154, number of events= 48
##
## coef exp(coef) se(coef) z Pr(>|z|)
## TreatmentCleansing -0.5614 0.5704 0.2934 -1.914 0.0557 .
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## exp(coef) exp(-coef) lower .95 upper .95
## TreatmentCleansing 0.5704 1.753 0.321 1.014
##
## Concordance= 0.566 (se = 0.039 )
## Likelihood ratio test= 3.73 on 1 df, p=0.05
## Wald test = 3.66 on 1 df, p=0.06
## Score (logrank) test = 3.76 on 1 df, p=0.05
#Building with treatement and burnpercentage
burn.cox.indep.TPB <- coxph(survTimeIndep ~ Treatment + PercentBurned, data = burn1)
summary(burn.cox.indep.TPB)
## Call:
## coxph(formula = survTimeIndep ~ Treatment + PercentBurned, data = burn1)
##
## n= 154, number of events= 48
##
## coef exp(coef) se(coef) z Pr(>|z|)
## TreatmentCleansing -0.524764 0.591695 0.295769 -1.774 0.076 .
## PercentBurned 0.007248 1.007275 0.007145 1.015 0.310
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## exp(coef) exp(-coef) lower .95 upper .95
## TreatmentCleansing 0.5917 1.6901 0.3314 1.056
## PercentBurned 1.0073 0.9928 0.9933 1.021
##
## Concordance= 0.585 (se = 0.046 )
## Likelihood ratio test= 4.7 on 2 df, p=0.1
## Wald test = 4.72 on 2 df, p=0.09
## Score (logrank) test = 4.82 on 2 df, p=0.09
#Building with treatement, burnpercentage, and burn Type
burn.cox.indep.TPBbt <- coxph(survTimeIndep ~ Treatment + PercentBurned + BurnType, data = burn1)
summary(burn.cox.indep.TPBbt)
## Call:
## coxph(formula = survTimeIndep ~ Treatment + PercentBurned + BurnType,
## data = burn1)
##
## n= 154, number of events= 48
##
## coef exp(coef) se(coef) z Pr(>|z|)
## TreatmentCleansing -0.537948 0.583945 0.300822 -1.788 0.0737 .
## PercentBurned 0.008986 1.009027 0.007301 1.231 0.2184
## BurnTypeScald 1.057604 2.879465 1.085913 0.974 0.3301
## BurnTypeElectric 2.265027 9.631385 1.083574 2.090 0.0366 *
## BurnTypeFlame 0.890441 2.436204 1.019409 0.873 0.3824
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## exp(coef) exp(-coef) lower .95 upper .95
## TreatmentCleansing 0.5839 1.7125 0.3238 1.053
## PercentBurned 1.0090 0.9911 0.9947 1.024
## BurnTypeScald 2.8795 0.3473 0.3428 24.190
## BurnTypeElectric 9.6314 0.1038 1.1517 80.543
## BurnTypeFlame 2.4362 0.4105 0.3304 17.965
##
## Concordance= 0.654 (se = 0.044 )
## Likelihood ratio test= 12.95 on 5 df, p=0.02
## Wald test = 14.22 on 5 df, p=0.01
## Score (logrank) test = 15.56 on 5 df, p=0.008
#Building with treatement, burnpercentage, and burn Type + Respartory Tract
burn.cox.indep.TPBbtResp <- coxph(survTimeIndep ~ Treatment + PercentBurned + BurnType + SiteRespTract, data = burn1)
summary(burn.cox.indep.TPBbtResp)
## Call:
## coxph(formula = survTimeIndep ~ Treatment + PercentBurned + BurnType +
## SiteRespTract, data = burn1)
##
## n= 154, number of events= 48
##
## coef exp(coef) se(coef) z Pr(>|z|)
## TreatmentCleansing -0.536426 0.584835 0.300473 -1.785 0.0742 .
## PercentBurned 0.008111 1.008144 0.007588 1.069 0.2851
## BurnTypeScald 1.083037 2.953636 1.087820 0.996 0.3194
## BurnTypeElectric 2.278658 9.763566 1.084165 2.102 0.0356 *
## BurnTypeFlame 0.851236 2.342540 1.024638 0.831 0.4061
## SiteRespTractBurned 0.140348 1.150675 0.351875 0.399 0.6900
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## exp(coef) exp(-coef) lower .95 upper .95
## TreatmentCleansing 0.5848 1.7099 0.3245 1.054
## PercentBurned 1.0081 0.9919 0.9933 1.023
## BurnTypeScald 2.9536 0.3386 0.3503 24.906
## BurnTypeElectric 9.7636 0.1024 1.1662 81.743
## BurnTypeFlame 2.3425 0.4269 0.3144 17.453
## SiteRespTractBurned 1.1507 0.8691 0.5773 2.293
##
## Concordance= 0.649 (se = 0.044 )
## Likelihood ratio test= 13.11 on 6 df, p=0.04
## Wald test = 14.27 on 6 df, p=0.03
## Score (logrank) test = 15.66 on 6 df, p=0.02
#Building with treatement, burnpercentage, and burn Type + resp Tract and gender
burn.cox.indep.TPBbtRespG <- coxph(survTimeIndep ~ Treatment + PercentBurned + BurnType + SiteRespTract + Gender, data = burn1)
summary(burn.cox.indep.TPBbtRespG)
## Call:
## coxph(formula = survTimeIndep ~ Treatment + PercentBurned + BurnType +
## SiteRespTract + Gender, data = burn1)
##
## n= 154, number of events= 48
##
## coef exp(coef) se(coef) z Pr(>|z|)
## TreatmentCleansing -0.590227 0.554202 0.302088 -1.954 0.0507 .
## PercentBurned 0.007192 1.007218 0.007599 0.946 0.3439
## BurnTypeScald 1.078282 2.939625 1.088765 0.990 0.3220
## BurnTypeElectric 2.157086 8.645907 1.087701 1.983 0.0473 *
## BurnTypeFlame 0.843227 2.323853 1.024277 0.823 0.4104
## SiteRespTractBurned 0.169939 1.185232 0.356008 0.477 0.6331
## GenderFemale -0.549411 0.577290 0.397753 -1.381 0.1672
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## exp(coef) exp(-coef) lower .95 upper .95
## TreatmentCleansing 0.5542 1.8044 0.3066 1.002
## PercentBurned 1.0072 0.9928 0.9923 1.022
## BurnTypeScald 2.9396 0.3402 0.3480 24.834
## BurnTypeElectric 8.6459 0.1157 1.0256 72.889
## BurnTypeFlame 2.3239 0.4303 0.3121 17.301
## SiteRespTractBurned 1.1852 0.8437 0.5899 2.381
## GenderFemale 0.5773 1.7322 0.2647 1.259
##
## Concordance= 0.682 (se = 0.043 )
## Likelihood ratio test= 15.22 on 7 df, p=0.03
## Wald test = 16 on 7 df, p=0.03
## Score (logrank) test = 17.39 on 7 df, p=0.02